In Konstant U.S. Pat. No. 4,915,240 and elsewhere rolling racks are disclosed in which at least first and second wheeled carts are mounted in rolling relation with a pair of rails. The respective carts roll over each over, with one cart being higher to accomplish this, so that the respective cart may all be presented in a vertically stacked array at the front end of the rack. Then, as pallets of the like are to be stored, they are placed one by one on each rolling rack, which is then rolled rearwardly by the emplacement of another pallet on the rack below a rolling rack that carries a pallet. Finally, the last pallet can be placed on the front end of the rails.
Other patents that teach various designs of rolling racks include Doring U.S. Pat. No. 4,341,343 and Konstant et al. U.S. Pat. Nos. 4,462,500 and 4,613,270, as well as Seiz et al. U.S. Pat. No. 4,687,404.
In the previously cited Konstant U.S. Pat. No. 4,915,240 pairs of overlapping carts are disclosed which roll on the same track surfaces. To provide substantial free rolling of individual carts over a limited distance, the front wheels of the upper cart are positioned between the front and rear wheels of the lower cart, so that the upper cart can roll rearwardly, carrying a pallet or the like without causing motion of the lower cart, until the front wheels of the upper cart collide with the rear wheels of the lower cart. Thus, if the lower cart is long enough, the upper cart can be pushed backward far enough to permit a pallet to be placed on the lower cart after a pallet has been placed on the upper cart.
While the above system works well, it does require that at least the lower carts must be of extended length, over and above what they would normally have to be to receive a pallet.
In accordance with this invention, a rolling pallet system is provided in which the respective carts do not have to be of extra length, while the same rail surfaces may be used by both carts. In this invention, the upper cart can be moved rearwardly as far as desired without engaging any wheels of a lower cart, which provides an added advantage to this invention.
It is also preferred for the carts of this invention to be modified to receive a slipsheet, skid or the like. A "skid" is a support structure for merchandise or other articles which has only two stringers and a top board, typically without middle support. The two stringers are positioned on opposed edges of the top board. Alternatively, there are other kinds of skids which may have multiple legs, extending downwardly from a board, which legs are made of coiled cardboard or the like. A nine legged skid is typically used. By this invention racks for use with slipsheets and skids of both types may be provided.